Suitability of phytoliths as a quantitative process tracer for soil erosion studies

Abstract

Phytoliths are plant microfossils commonly used as qualitative archive markers in archaeological and paleoecological studies. Their potential uniqueness to the vegetation cover, robustness to weathering, and lack of chemical alteration along the transport paths make them potentially suitable tracers for quantitative erosion studies. In this pilot study, we explore the potential of phytoliths in a sediment fingerprinting study in the Ceguera catchment (28 km2) in NE Spain. The phytolith concentrations and morphologies of four land cover classes (agricultural land, badland, forest, and shrubland) were analysed, and their contributions to four natural sediment mixture samples along the river course were modelled. Phytolith concentrations allowed us to discriminate sources sufficiently, albeit with limited sample size. The performance of the phytoliths as tracer was tested by reproducing the sources of artificial sediment mixture samples with satisfactory recall ratio. Results identified badlands to be the main contributor, with 84–96% of the sediment load to the sinks, followed by shrublands (median 5%) and agricultural lands (median 2%). These major findings can be reproduced by other conventional erosion studies from this area, indicating that phytoliths are suited to quantifying erosion patterns in mesoscale catchments.

Oil-palm management alters the spatial distribution of amorphous silica and mobile silicon in topsoils

“…To our knowledge, only a few studies exist in which the effect of soil erosion on the topsoil Si Am pool has been addressed. Almost all of them focused on arable soils (Clymans et al, 2015;Unzué-Belmonte et al, 2017;Kraushaar et al, 2021). Clymans et al (2015) determined mean topsoil Si Am concentrations of 1.76 mg −1 g −1 in arable fields in sloping terrain and temperate climate.…”

“…After LULC transformation from forest to arable land, Si can be lost from the system through harvest, topsoil erosion, and increased Si leaching in soil. Si leaching in soil is triggered by reduced interception which results in increased percolation (Keller et al, 2012;Vandevenne et al, 2012;Kraushaar et al, 2021). Si-accumulating plants such as rice, wheat, barley, maize, and oil palm (Ma and Takahashi, 2002;Munevar and Romero, 2015) are characterized by Si accumulation of >1 wt % in dry leaf tissue and a Si / Ca ratio >1 (Ma and Takahashi, 2002).…”

Fitólitos – Uma ferramenta para estudos de reconstituição paleoambiental

“…Entretanto, quando bem compreendida as questões fluviais e geomorfológicas envolvidas, o emprego dos fitólitos pode ser uma importante ferramenta, tal como observado nos estudos de NEUMANN et al (2009), SANGEN et al (2011), GARNIER et al (2013 Por outro lado, os fitólitos, quando aplicados a estudos fluviais de pequenas bacias hidrográficas e de erosão possuem singular potencial em relação à cobertura vegetal, à robustez, às intempéries e baixa alteração química ao longo dos caminhos de deslocamento dos sedimentos. Estas características fazem dos fitólitos potenciais e adequados traçadores para estudos quantitativos de erosão (KRAUSHAAR et al 2021).…”

Special issue: German Society for Geomorphology

“…Kraushaar et al ( 2021 ) investigated the potentials and challenges of phytoliths as a quantitative process tracer for soil erosion in a medium‐size sub‐catchment of the Isábena River in the Spanish Pyrenees. The results of this pilot study show that the phytolith assemblages examined seem to be unique to land cover classes, constant in time for the observed timescale of recent erosion, and physically and chemically conservative on site, during transport and deposition.…”